The present invention provides a fluid distribution conduit. More specifically, a conduit apparatus incorporating multiple nozzle ports and individual calming regions for each port is provided for a cooling tower.
Evaporative cooling equipment such as cooling towers, evaporative condensers, and closed circuit fluid cooling towers have been used for many years to reject heat to the atmosphere. Cooling towers typically operate by distributing the water to be cooled over the top of a heat transfer surface and passing the water through the heat transfer section while contacting the water with air. As a result of this contact, a portion of the water is evaporated into the air thereby cooling the remaining water.
In closed-circuit cooling towers and evaporative condensers, the fluid to be cooled, or the refrigerant to be condensed, is contained within a plurality of closed conduits. Cooling is accomplished by distributing cooling water over the outside of the conduits while at the same time contacting the cooling water with air.
In all applications of evaporative cooling equipment, proper water distribution within the equipment is critical to efficient performance of the equipment. Uneven distribution of water to the heat transfer surface will reduce the available air-to-water interfacial surface area, which is necessary for heat transfer. Severe misdistribution of water may result in air flow being blocked through those areas of the heat transfer media which are flooded with water while at the same time causing air to bypass those areas of the media which are starved of water.
Generally, water distribution systems used in evaporative cooling equipment are either of the gravity-feed type or the pressure-spray type. Gravity-feed distribution systems typically comprise a basin or pan which is positioned above the heat transfer media. In the bottom of the basin are positioned nozzles which operate to gravitationally pass water contained in the basin through the bottom of the basin while breaking up the water into smaller droplets and distributing the water droplets to the underlying heat transfer surface.
Pressure-spray distribution systems, typically comprise multiple water distribution ranches, or headers, positioned above the heat transfer media with each branch containing a multitude of small spray nozzles. Generally, these nozzles are arranged closely in a uniform spacing in an attempt to achieve even water distribution across the typically rectangular top of the heat transfer surface.
U.S. Pat. No. 5,431,858 to Harrison, Jr. discloses a fluid distribution system for continuously distributing hot fluid evenly across the top face of a fill assembly in a cross-flow water cooling tower. This disclosure provided a uniform fluid head to the distribution pan and provides an in-line basket filter to prevent clogging of the metering nozzles in the pan. Further, this apparatus was arranged to conserve the total energy of the flowing water, especially the velocity component, and to advantageously utilize that energy.
It is also desired to keep the overall height of the cooling equipment to a minimum, which necessitates positioning the spray distribution system at a minimum distance above the top of the heat transfer surface. The closer the distribution system is to the top of the heat transfer surface, the less room there is for the water to be distributed and the less surface area the spray from each nozzle is generally able to cover.
In the present environmentally conscious era, conservation of energy is of critical importance to minimize the required spray water pumping pressure. Typically, pressure spray distribution systems have operated at spray pressures in the range of 3 to 8 psig. However, it is now desired to operate with spray pressures of no greater than 3 psig. This is especially true in very large towers where a very small increase in spray pressure requirements can increase unit operating costs by hundreds of thousands of dollars over the lifetime of a unit. Achieving uniform water distribution at low spray pressures is very difficult. This is due to the fact that at low spray pressures, there is very little energy available from the spray pressure to assist in spreading and distributing the water flow through the spray nozzles.
A potential method to distribute water in a large cooling tower would be to simply increase the size of the components of the distribution systems which have been successfully used on smaller cooling towers. However, as a practical matter this is not feasible as an increase in the distribution system size requires an increase in all dimensions of the distribution system by a proportional amount, including an increase in tower height. U.S. Pat. No. 4,208,359 to Bugler, III et al. describes a low pressure head, non-clogging water distribution system for large cooling towers. The nozzle emits a hollow cone of water which impacts a circular deflecting structure for production of a full cone of water.
Another problem to be accommodated in the pressure-spray type distribution systems is the avoidance of high fluid-velocity of effects of the water flow past the nozzles, which can induce a shearing effect. This shearing inhibits adequate liquid feed to the individual nozzles in the water distribution branch and uneven water flow to the top surface of the media or the top area of the heat transfer surface.
The present invention provides distribution branches for a pressure-spray type liquid distribution system. The distribution branches can accommodate substantially all of the nozzles presently provided on closely aligned branches extending from a common spray header, but the number of branches can be significantly reduced. The distribution branch of the present invention allows, or will tolerate, the high fluid velocities of present liquid distribution systems, but it will avoid the shearing effect above individual nozzles and provide a calming or stilling region above the nozzle for generally non turbulent liquid flow to individual nozzles. In an alternative embodiment, the individual branches can be provided with nozzles in about their present locations as well as providing the protuberances with the calming regions open to the fluid channel of the branch but displaced from the direction of fluid flow along this fluid channel. Reduction of the number of fluid carrying branches is a more ready access for servicing the area below the branches and above the heat transfer surface.